With the high-speed operations of high-end servers and super computers, a method of transmitting optical signals in a substrate tends to be used instead of a method of transmitting electrical signals in a substrate. A photoelectric conversion module (optical module) performs a conversion from an optical signal into an electrical signal or a conversion from an electrical signal into an optical signal.
As illustrated in FIG. 11, an optical module 101 is disposed around a semiconductor device 300 such as, for example, a central processing unit (CPU) chip mounted on a main board 201, via an interposer 102. An optical fiber 103 is connected to the optical module 101.
A semiconductor chip 301 which is included in the semiconductor device 300 is mounted on a package substrate 302. The package substrate 302 is mounted on the main board 201 via ball grid array (BGA) balls 303. A heat sink 305 is mounted on the semiconductor chip 301 via a lead 304. A transmission path from the semiconductor chip 301 to the optical module 101 follows the sequence of the semiconductor chip 301, the package substrate 302, the BGA balls 303, the main board 201, the interposer 102, and the optical module 101.
In order to reduce a latency and transmission loss, the length of the electrical transmission path may be reduced by mounting the optical module 101 at a position near the semiconductor chip 301, and reducing the number of electrical contacts. Although the trend is oriented toward a method of directly receiving and transmitting optical signals from the inside of a CPU package (e.g., a multi-chip module (MCM) or silicon photonics), many technical problems remain for practical application thereof.
As illustrated in FIG. 12, there is a case where the optical module 101 is mounted on the package substrate 302. A transmission path from the semiconductor chip 301 to the optical module 101 follows the sequence of the semiconductor chip 301, the package substrate 302, the interposer 102, and the optical module 101.
The cooling of the optical module 101 is performed because the optical module 101 generates heat during the driving thereof. In order to cool the optical module 101, a cooling mechanism is separately mounted on the optical module 101. When the mounting position of the optical module 101 is close to the semiconductor chip 301, the cooling mechanism mounted on the optical module 101 and the heat sink 305 mounted on the semiconductor chip 301 may physically interfere with each other.
The followings are reference documents.
[Document 1] International Publication Pamphlet No. WO 2009/113180 and
[Document 2] Japanese Laid-Open Patent Publication No. 2003-043311.